Spin Current Generation and Detection in the Presence of AC Gate

We predict that in a narrow gap III-V semiconductor quantum well or a wire an observable spin current can be generated with a time dependent gate to modify the Rashba spin-orbit coupling constant. Methods to rectify the so generated AC current are discussed. An all-electric method of spin current detection is suggested, which measures the voltage on the gate in the vicinity of a 2D electron gas carrying a time dependent spin current. Both the generation and detection do not involve any optical or magnetic mediators.